Microsoft on Thursday released an out-of-band patch, MS10-002, to address eight vulnerabilities in Internet Explorer, a move prompted by the revelation last week that a series of cyber attacks from China on Google and some 33 other companies relied on a flaw in Microsoft's browser.

The eight vulnerabilities are rated "critical" in most cases and have an Exploitability Index rating of 1, meaning that exploit code is likely. In fact, proof-of-concept exploit code has already been reported and malicious exploit code is circulating online.

Microsoft is urging customers to install this update as soon as possible. The vulnerabilities affect Internet Explorer versions 5-8 and Windows 2000, XP, Vista, 7, Server 2003, and Server 2008.
The company maintains that it has only seen limited and targeted attacks against Internet Explorer 6. But other security companies see broader risk affecting users of Internet Explorer 7 and 8.

Symantec on Wednesday said that it had detected a new exploit that attempts to leverage one of Internet Explorer's current vulnerabilities.

Josh Talbot, security intelligence manager at Symantec Security Response, said in an e-mailed statement that the new exploit, called Trojan.Malscript!html, has been detected on hundreds of Web sites. He said that the malicious code bypasses a warning dialog box that Internet Explorer shows after downloading a file. The malicious code calls APIs in a way that may prevent API monitoring, a technique used by some security software to detect malicious activity.

On Wednesday, Microsoft also released Security Advisory 979682, which describes an Elevation of Privilege (EoP) vulnerability in the Windows kernel that affects 32-bit versions of Windows.

To exploit this vulnerability and obtain administrative privileges, an attacker must already have a local account and log in locally. Microsoft said it isn't aware of attempts to exploit this vulnerability and has provided workaround information.